Polymerization of olefin/carbon monoxide with non-transition metal salt, bidentate p ligand and carboxylic acid ester

ABSTRACT

The process of producing linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon in the presence of novel catalyst composition prepared from a palladium compound, a non-transition metal salt of a non-hydrohalogenic acid having a pKa less than 6, bidentate phosphorus ligand and a ketone or ester carboxylic compound.

This is a division of application Ser. No. 061,615, filed June 15, 1987now U.S. Pat. No. 4,810,774.

This invention relates to a process for the production of polymers ofcarbon monoxide and ethylenically unsaturated hydrocarbon and to certainnovel catalyst compositions useful in such process.

High molecular weight copolymers or terpolymers of carbon monoxide andone or more ethylenically unsaturated hydrocarbons are often referred toas polyketones. These polymers are linear, alternating polymers ofcarbon monoxide and at least one olefinic moiety polymerized through theethylenic unsaturation of the hydrocarbon. For example, when theethylenically unsaturated hydrocarbon is ethylene, the copolymerconsists of units of the formula --CO--C₂ H₄ --. The polyketones aretypically prepared by reacting carbon monoxide and the ethylenicallyunsaturated hydrocarbon(s) in the presence of a Group VII metal, e.g.,palladium, the anion of an non-hydrohalogenic acid having a pKa lessthan 6 and a bidentate ligand of the formula R¹ R² --M--R--MR³ R⁴wherein R¹, R², R³ and R⁴ are organic radicals, R is a bivalent organicbridging group and M is phosphorus, arsenic or antimony.

For some polymerization applications, the anion catalyst component isusefully provided as the free acid. In other applications the anion isprovided as a salt of the acid. However, use of a salt as the source ofthe desired anion frequently results in a decrease of catalyst activity.When the anion source is the salt of a transition metal, addition of aquinone such as 1,4-benzoquinone results in improved activity. When thesalt is a non-transition metal, hydroquinones are not particularlyeffective. Addition of an ether to a catalyst composition derived from anon-transition metal salt does result in increased activity. However,for some applications an alternative to the use of ethers as catalystmodifier is desired.

SUMMARY OF THE INVENTION

The process of the invention contemplates the formation of linear,alternating polymers by polymerization of carbon monoxide with at leastone ethylenically unsaturated hydrocarbon in the presence of a catalystcomposition prepared from a palladium compound, a non-transition metalsalt of a non-hydrohalogenic acid having a pKa less than 6, a bidentatephosphorus ligand and a ketone or ester carboxylic compound. Theinvention further contemplates the novel catalyst compositions useful inthe process of the invention.

DESCRIPTION OF THE INVENTION

In the process of the invention, carbon monoxide is polymerized with atleast one ethylenically unsaturated hydrocarbon. Preferred hydrocarbonsare hydrocarbons of 2 to 20 carbon atoms inclusive, more preferably 2 to10 carbon atoms inclusive. Such hydrocarbons are wholly aliphatic,including α-olefins such as ethylene, propylene, butene-1 and octene-1,or arylaliphatic olefins containing an aryl substituent on a carbon atomof the ethylenic unsaturation such as styrene, p-methylstyrene andp-ethylstyrene. Preferred embodiments of the process of the inventionprepare polymers of carbon monoxide and ethylene or terpolymers ofcarbon monoxide, ethylene and an aliphatic α-olefin, particularlypropylene.

The molar ratio of unsaturated hydrocarbon to carbon monoxide in thepolymerization mixture varies from about 10:1 to about 1:5, preferablyfrom about 5:1 to about 1:2. When ethylene and a second ethylenicallyunsaturated hydrocarbon are employed to produce a terpolymer with carbonmonoxide, the molar ratio of ethylene to other unsaturated hydrocarbonis preferably from about 400:1 to about 1:1 with ratios from about 100:1to about 2:1 being preferred.

The palladium compound employed in the novel catalyst composition of theinvention is a palladium salt of an organic acid, preferably acarboxylic acid of up to about 10 carbon atoms. In part for ease ofprocurement, palladium acetate is a particularly preferred source ofpalladium compound although palladium propionate or palladium hexanoateare also suitable.

The palladium compound is employed in conjunction with certain salts ofacids having a pKa less than about 6, preferably less than about 2, asdetermined in aqueous solution at 18° C. Suitable acids areoxygen-containing acids and are inorganic acids such as sulfuric acid orperchloric acid or are organic acids including carboxylic acids such astrichloroacetic acid, difluoroacetic acid and trifluoroacetic acid, andsulfonic acids such as methanesulfonic acid, trifluoromethanesulfonicacid and para-toluenesulfonic acid. Trifluoroacetic acid andpara-toluenesulfonic acid are a preferred class of organic acids. Themetal salts of these acids contain a non-transition metal, andparticularly a metal or Group IA to Group VA of the Periodic Table ofElements. Illustrative of metals whose salts are useful in the catalystcomplexes of the invention are the Group IA metals lithium, sodium andpotassium, the Group IIA metals magnesium and calcium, the Group IIIAmetals aluminum and gallium, the Group IVA metals tin and lead and theGroup VA metal antimony. The Group IA metals constitute a preferredclass of the non-transition metals, especially sodium and potassium.

The metal salt, like the palladium compound, is employed in a catalyticamount. For each mole of ethylenically unsaturated compound to bepolymerized, from about 1×10⁻⁷ mol to about 1×10⁻³ mol of palladiumcompound is employed, preferably from about 1×10⁻⁶ mol to about 1×10⁻⁴mol. The metal salt is employed in a quantity from about 0.5 equivalentsto about 200 equivalents per gram-atom of palladium (as the compound).Amounts of metal salt from about 1 to about 100 equivalents pergram-atom of palladium are preferred.

The bidentate phosphorus ligand of the invention has the formula##STR1## in which R¹, R², R³ and R⁴ independently are an organicradicals of from 1 to 14 carbon atoms inclusive, but preferably arearyl, alkaryl or alkoxyaryl, such as phenyl, alkylphenyl or alkoxyphenylgroups. Phenyl, para-tolyl and p-methoxyphenyl groups are particularlypreferred. The group R is a divalent bridging group of up to 20 carbonatoms, with up to three carbon atoms in the bridge, and is hydrocarbylor substituted hydrocarbyl wherein any substituent is di(R¹)P-alkyl.Examples of suitable bidentate ligands are1,3-bis(di-p-tolylphosphino)propane,1,3-bis(di-p-methoxyphenylphosphino)propane,1,3-bis(diphenylphosphino)propane, and2-methyl-2-(methyldiphenylphosphino)-1,3-bis(diphenylphosphino)propane.The preferred bidentate ligand is 1,3-bis(diphenylphosphino)propane. Theligand is utilized in a quantity from about 0.1 to about 5 mol per molof palladium compound and preferably from about 0.5 to about 1.5 mol permol of palladium compound.

The ketone or ester carboxylic compound used as a catalyst componentcontains from 3 to 20 carbon atoms inclusive, preferably 3 to 10 carbonatoms inclusive, is acyclic or cyclic and is an otherwise hydrocarbylester or ketone or is substituted hydrocarbyl with non-hydrocarbylsubstituents such as hydroxyl, halo or alkoxy which are inert underpolymerization conditions, e.g. being free of ethylenic unsaturation.The ester of ketone carboxylic compounds are aliphatic, aromatic, ormixed aliphatic and aromatic and are mono-functional esters or ketones,e.g., mono-esters, or are difunctional ketones or esters such asdiesters of dicarboxylic acids. Examples of suitable ketones arealiphatic ketones such as acetone, methyl ethyl ketone, diethylketone,2,5-hexanedione, cyclopentanone, cyclooctanone and ketones with an arylsubstituent include acetophenone and benzophenone. Illustrative estersinclude methyl acetate, ethylpropionate, dimethyl carbonate and diethyloxylate, butyrolactone, ethylene glycol diacetate, propylene glycoldiacetate and methyl benzoate. Substituted hydrocarbyl esters andketones include chloroacetone, methoxydiethylketone, methoxymethylpropionate, and ethylene glycol monoacetate. Also useful are compoundswith both ketone and ester moieties such as methyl 3-oxo-hexanoate.Largely for reasons of availability, hydrocarbyl carboxylic compounds,and particularly acetone and ethylene glycol diacetate are preferred.

The ester component is employed in a quantity from about 0.5 mol toabout 10,000 mol per mole of metal salt, preferably from about 1 mol toabout 5000 mol per mol of metal salt.

The polymerization process of the invention is conducted underpolymerization conditions in the presence of an alcohol diluent as aliquid phase. Suitable diluents are alkanols of up to 8 carbon atoms,preferably methanol or ethanol. Useful polymerization temperatures arefrom about 20° C. to about 200° C. and in particular from about 30° C.to about 150° C. Suitable polymerization pressures vary from about 1 barto about 200 bar, preferably from about 20 bar to about 100 bar. Themethod of contacting the reactants and catalyst is not critical and maybe accomplished by stirring or shaking. Subsequent to polymerization,the product mixture components are separated and the polymer recoveredby conventional methods such as filtration or decantation. On occasion,the polymer contains catalyst residues which may be removed, if desired,by treatment with a solvent selective for the catalyst residues present.

The invention is illustrated further by the following IllustrativeEmbodiments and Comparative Experiments. All of the copolymers preparedaccording to the invention and isolated had melting points of 257° C.and were shown by ¹³ NMR analysis to have a linear, alternatingstructure.

COMPARATIVE EXAMPLE I

(A) A magnetically-stirred autoclave was charged with 0.1 mmol ofpalladium acetate, 0.15 mmol of 1,3-bis(diphenylphosphino)propane and 1mmol of potassium para-tosylate (p-toluenesulfonate) in 50 ml ofmethanol. Carbon monoxide was introduced until a pressure of 30 bar wasreached and ethylene was added until a pressure of 60 bar was reached.The autoclave was heated to 80° C. and maintained at that temperaturefor 5 hours. The autoclave was then cooled to room temperature and thepressure released. A very small quantity of polymer was obtained.

(B) Essentially the same result was obtained when 1 mmol of lithiump-tosylate was used in place of the potassium p-tosylate.

COMPARATIVE EXAMPLE II

The procedure of the first part of Comparative Example I was repeatedwith the addition of 10 mmol of 1,4-benzoquinone to the reactionmixture. Again, no more than a trace of polymer was obtained.

ILLUSTRATIVE EMBODIMENT I

The procedure of part A of Comparative Experiment I was repeated withthe following differences. The catalyst solution additionally contained20 ml of ethylene glycol diacetate and the reaction mixture, subsequentto cooling and venting of the reactor, was filtered to remove polymerwhich was washed with methanol and dried in vacuo at room temperature.The yield of copolymer was 16 grams. Accordingly, the calculatedpolymerization rate was 320 g of copolymer/g of Pd/hour.

ILLUSTRATIVE EMBODIMENT II

The procedure of Illustrative Embodiment I was repeated, except that 20ml of acetone was employed in place of the ethylene glycol diacetate.The yield of copolymer was 15 g, produced at the calculated rate of 300g of copolymer/g Pd/hr.

COMPARATIVE EXAMPLE III

The procedure of Illustrative Embodiment I was repeated except that noethylene glycol diacetate was employed, 1 mmol of tin sulfate was usedin place of the potassium p-tosylate and the reaction time was 1 hour.The yield of copolymer was 5 g, produced at a calculated rate of 500 gof copolymer/g Pd/hr.

COMPARATIVE EXAMPLE IV

The procedure of Comparative Example III was repeated, except that 10mmol of 1,4-benzoquinone was added to the catalyst solution. The yieldof copolymer was 5 grams, produced at a calculated rate of 500 g ofcopolymer/g Pd/hr.

COMPARATIVE EXAMPLE V

The procedure of Illustrative Embodiment I was repeated, except that noethylene glcyol diacetate was employed. 2 mm of antimony sulfate wereused instead of 1 mmol of potassium p-tosylate and the reactiontemperature was 55° C. A yield of 17.5 g of copolymer was obtained,produced at a calculated rate of 350 g of copolymer/g Pd/hr.

ILLUSTRATIVE EMBODIMENT III

The procedure of Comparative Example V was repeated except that 20 ml ofethylene glycol diacetate was added to the catalyst solution and thereaction time was 2 hours. The yield of copolymer was 17 g, produced ata calculated rate of 850 g of copolymer/g Pd/hr.

ILLUSTRATIVE EMBODIMENT IV

When the procedures of the above Illustrative Embodiments are repeatedin the additional presence of an amount of propylene, a terpolymer ofcarbon monoxide, ethylene and propylene will be obtained.

The polymers of the invention are known polymers and have goodmechanical properties. They are processed by means of the usualtechniques into films, sheets, plates, fibers and molded objects, forexample. The relatively low molecular weight polymers in particular areused as components in blends with other polymers having applications aswaxes or greases as well as having utility as plasticizers for otherpolymers. The higher molecular weight polymer products find utility aspremium thermoplastics for fibers, films, and injection or compressionmolding applications. Because of their properties, the higher molecularweight polymers are suitable for applications in the auto industry, inthe manufacture of containers for food and drinks, as construction andbuilding material and a variety of similar applications. The polymersare modified by mixing or blending with other polymeric materials toproduce mixtures or blends having varied and widespread application.

What is claimed is:
 1. The process of producing a linear, alternatingpolymer of carbon monoxide and at least one ethylenically unsaturatedhydrocarbon of 2 to 20 carbon atoms inclusive, by contacting carbonmonoxide and said hydrocarbon under polymerization conditions in thepresence of a catalyst composition prepared from a palladium compound, anon-transition metal salt of non-hydrohalogenic acid having a pKa lessthan about 6, a bidentate phosphorus ligand of the formula R¹ R²--P--R--P--R³ R⁴ in which R¹, R², R³ and R⁴ independently are organicradicals of from 1 to 14 carbon atoms inclusive and R is a divalentbridging group of up to 20 carbon atoms and up to three carbon atoms inthe bridge, and a carboxylic ester of from 3 to 20 carbon atomsinclusive that is a hydrocarbyl ester or substituted hydrocarbyl esterwith substituents which are inert under polymerization conditions, saidsubstituents being selected from hydroxyl, halo or alkoxy group, saidcarboxylic ester being free from ethylenic unsaturation.
 2. The processof claim 1 wherein at least one unsaturated hydrocarbon is selected fromethylene or mixtures of ethylene and propylene.
 3. The process of claim2 wherein the unsaturated hydrocarbon is ethylene.
 4. The process ofclaim 2 wherein the metal salt is a non-transition metal salt of anoxygen-containing acid having a pKa less than about
 2. 5. The process ofclaim 4 wherein the metal salt is a salt of a Group IA to Group VAmetal.
 6. The process of claim 4 wherein each of R¹, R², R³ and R⁴ ofthe bidentate ligand is phenyl, alkylphenyl or alkoxyphenyl.
 7. Theprocess of claim 4 wherein the carboxylic ester is a hydrocarbon of 3 to10 carbon atoms inclusive.
 8. The process of claim 5 wherein thepalladium compound is palladium acetate.
 9. The process of claim 8wherein the carboxylic ester is ethylene glycol diacetate.
 10. Theprocess of claim 9 wherein the bidentate ligand is1,3-bis(diphenylphosphino)propane.
 11. The process of claim 10 whereinthe metal salt is a Group 1A metal salt.
 12. The process of claim 11wherein the Group IA metal salt is potassium para-toluenesulfonate. 13.The process of producing a linear, alternating polymer of carbonmonoxide and at least one ethylenically unsaturated hydrocarbon of 2 to20 carbon atoms inclusive, by contacting carbon monoxide and saidhydrocarbon under polymerization conditions in the presence of acatalyst composition prepared from a palladium compound, anon-transition metal sale of non-hydrohalogenic acid having a pKa lessthan about 6, a bidentate phosphorus ligand of the formula R¹ R²--P--R--P--R³ R⁴ in which R¹, R², R³ and R⁴ independently are organicradicals of from 1 to 14 carbon atoms inclusive and R is a divalentbridging group of up to 20 carbon atoms and up to three carbon atoms inthe bridge, and a carboxylic ester of from 3 to 20 carbon atomsinclusive, said ester being selected from the group consisting of methylacetate, ethylpropionate, dimethyl carbonate, diethyl oxylate,butyrolactone, ethylene glycol diacetate, propylene glcyol diacetate,methyl benzoate or ethylene glycol monoacetate.
 14. The process of claim13 where the ester is ethylene glycol monoacetate.